1. Field of the Invention
The present invention relates to switching mechanisms for networks, and in particular to reconnection of network channels.
2. Description of the Prior Art
Global networks are common to all of todays telecommunication and other network systems, wherein various data, optical, and wireless devices are interconnected by a series of individual local networks. The networks generally consist of nodes and links, which describe the network topology, and associated attributes which comprise the network data. Furthermore, these networks further contain management systems that must co-ordinate the transmission of data traffic, including voice, video, and data, and other information over a variety of transmission mediums, such as wireless, copper, and fiber optic lines.
Many of todays telecommunication networks are in nearly continuous use and can ill afford instances of “down” or “off-line” time in the event of network element failure or maintenance and update procedures. Furthermore, telecommunication networks increasingly require control software and hardware that should have little or no scheduled down time. However, these same network systems require cost effective computing solutions, open architecture for supporting a variety of hardware and software formats, and the flexibility to implement the latest software and hardware updates as they become available. Accordingly, it is critical in todays telecommunication networks to provide and maintain the integrity of data communication in the event of disruption in the control and data flows, due to both anticipated and unanticipated interruptions.
Modern telecommunication networks and their support systems have evolved from static installations to dynamic systems, which need to implement and adapt to changes on a regular basis. These dynamic systems increasingly contain new collections of products that process a plurality of requests from a constantly changing user base, in an expected reliable environment. The ability of telecommunication networks to provide stable service availability in this dynamic environment is becoming increasingly important, as the innovation in products and customer environments is expected to increase.
In traditional networks, control flow and data flow were coupled for communication traffic between various network elements. Accordingly, it was typical that both the data and control flows failed at the same time during network interruptions. However, todays telecommunication networks are characterized by the separation of the control and data flows, as the data channels and their operation are somewhat independent from the control channels and their associated software controllers. For example, in optical switches, the lasers and other optical elements can continue to transmit data even in the event that their corresponding optical connection controller experiences either line or module failure. Therefore, during failure events the data channels and control channels can become unsynchronized, such that rather than both being maintained in “up states” their states may alternate between unsynchronized up and down modes of operation. These mismatched operational states of the network for the data and control channels need to be resynchronized in a straightforward and efficient manner, so that the perception of network interruptions by the customer is minimized. Accordingly, during recovery or replacement of network elements the network is expected to resynchronize its state such that the new signaling element knows about the data elements that were previously allocated.
One traditional method of re-synchronization is the journaling technique. Accordingly, at each network element the journaling technique continuously journals (copies) the pertinent state information from the signaling element, such as control instructions and corresponding switch settings, on to spare hardware such as standby signaling elements or to a data element. Therefore, in the event of a network failure the new controller, software and/or hardware, can recover its state by accessing the journal by querying the data element, or if kept in sync by simply restarting. However, this resynchronization method requires dedicated spare hardware for backup storage purposes. Furthermore, the operational speed for such journalling systems is slower as the state information must be stored as it is created and/or changed in the network, and correspondingly these journal copies must be deleted when these network connections are removed. A further disadvantage of the journaling technique is in the deployment of new or enhanced hardware/software, which should be compatible with the old versions on the backup hardware. Further, these new deployments or enhancements must also be journaled, as well as any changes to the copying/journaling protocols resulting from related control protocol modification. Accordingly, implementation of software and hardware updates over the network can be time consuming and problematic, when relying on the journaling technique for network reliability.
It is an object of the present invention to provide a resynchronization method and system to obviate or mitigate some of the above-presented disadvantages.